Thursday 25 October 2012 12.00 EDT
First published on Thursday 25 October 2012 12.00 EDT

So much for showbiz perks: Rory Kinnear can't even get a cup of tea. We're in a pub near London Bridge and Kinnear is pleading – ever so politely – with the barmaid. "Don't have the staff," she replies, face like stone. It's mid-afternoon last Wednesday. He settles for a half of bitter, looking sheepish and a touch guilty, like an accountant who's just missed a tax deadline.

I'm secretly hoping for a hissy fit, but within seconds of meeting him you sense this isn't really Kinnear's style. We're here to talk about his turn in Skyfall as Bill Tanner, M's long-serving, long-suffering sidekick, a drudge if ever there was one: the kind of spy who, if Bond lent him the Aston Martin, would only fret about where to park it. While 007's other modes of transport in this latest instalment include the roof of a train and a glossy luxury yacht, you can imagine Kinnear's version of Tanner breaking a sweat on the 7.32 to Waterloo.

On the face of it – Kinnear is charmingly eloquent on the shortcomings of his face and hairline – it seems like perfect casting. But that would be to misjudge what makes him one of the sharpest actors of his generation. Kinnear's defining talent is being indefinable. There aren't many actors who have tackled Denis Thatcher (in BBC4's The Long Walk to Finchley) and Brian Epstein (for another BBC project, Lennon Naked), still less followed them with one of Shakespeare's most enigmatic roles, Bolingbroke, in last summer's TV adaptation of the histories, The Hollow Crown.

His range on stage is still broader. Not only can he be outrageously funny – he stole the show (and won an Olivier) as a preening, ciao-ing Restoration fop at the National in 2007 – but he has also mastered some of the darkest roles in the repertoire: notably the Prince of Denmark himself. He is embarrassed when I mention this glittering roll-call – he had assumed his looks meant a long haul of murderers in TV detective series. He grins lopsidedly. "If my face popped up, you could pretty much guess whodunnit in the first five minutes."

But then came the Bond "juggernaut" (his word), which Kinnear was invited to leap aboard with Quantum of Solace. Though he is the first to admit that Tanner isn't a stretch ("someone said I should be commended for services to plot exposition"), he insists that playing MI6's desk-bound human Filofax is trickier than it looks. "The irony is, most of what I'm saying, I have not a clue what any of it means. There's a sequence where I'm bringing Bond back into MI6, filling him in on what's happened, and I literally just had to learn everything syllable by syllable." He looks deadpan. "You can probably see that in my eyes."

He doesn't seem the most absorbing character. "With a part that can be quite functional, actually that's the fun thing – you do have to create a living, breathing backstory." Still, he must have looked enviously on Daniel Craig's travel itinerary. "But on the upside, most of the time, I got to walk to work."

This, actually, is the surprising thing about Skyfall: although the producers have hardly lost their taste for exotic setpieces (a whole island off Macau! Forcibly depopulated!), they have opted to celebrate Bond's half-century on screen by serving up what might be his most domestic setting yet. In Sam Mendes's hands, as 007 claws his way through the bowels of London, chasing Javier Bardem's bulging-eyed baddie through tube tunnels and the Piranesian cathedrals of the sewage system, you wonder whether the hero of the piece is Bond himself, or the city he inhabits. The backroom boys, Tanner among them, get a turn in the spotlight; even Judi Dench's M ends up in the firing line – literally so, when the official inquiry she's summoned to turns into a Whitehall spin on the OK Corral.

'Most of what I'm saying, I haven't a clue what it means' … Rory Kinnear as Bill Tanner in Skyfall. Photograph: Francois Duhamel

More demanding has been his role in Broken, the debut feature by yet another theatrical alumnus, director Rufus Norris, part of critics' week at Cannes and warmly received at the London film festival. Though the budget is a squillionth of Skyfall's, its ambition is huge, and Kinnear is given a chance he must have been yearning for, to show what he's capable of on the big screen.

He plays a washed-up, recently widowed father of three living in a mouldering cul-de-sac – a ravening werewolf of a man whose ferocious adoration for his daughters results in psychopathic violence towards everyone else. One moment we see him ironing the family wash; the next he's smashing a guileless neighbour's forehead into the bonnet of a car.

"It's entirely to do with the fractured love he has for his family," Kinnear says, thoughtfully, "the grief he's going through. He's part of a culture that is unable to talk about emotions in a literate way, so he just lashes out."

Kinnear's gift to the role is his subtle balance between thuggish menace and bruising pathos: its emotional crux is a silent long shot of him pacing with bewildered sorrow in a hospital corridor, like a bear on the end of a chain. He shrugs. "You've got to find something that feels like an extension of yourself. That doesn't mean you're like these people, but that's the interesting thing about acting – recognising that there's so much we shut ourselves off from in order to function as civilised members of society. That's as true of Hamlet as of a guy living in a cul-de-sac."

Some have wondered whether – at least in one regard – Kinnear's interest in characters on the edge reflects his own experience: his father, Roy, a much-loved, much-admired character actor, was killed when Rory was 10, in a film stunt that went horribly wrong. Has his father's reputation ever weighed heavily? "No, actually. It's mainly journalists who ask. No one in the acting profession has anything but fond memories and funny stories. Pretty much everything I do, I'm given a little scrap that offers a greater picture of his life."

Since graduating from drama school 11 years ago, he has rarely been out of work. Things are especially busy at the moment: he's shooting a Channel 4 drama called Southcliffe, then it's rehearsals for Othello at his old roost the National, where he will play Iago to Adrian Lester's Moor. Home life is equally hectic: he and his wife Pandora Colin have a two-year-old son, and have just moved house ("no let-up," he says cheerily). Is he happy with Skyfall? He hasn't had time to see it yet.

I can't resist showing him a fansite I've dug up on the web. We scroll through images of Kinnear scrubbed up for the red carpet, manfully cresting the Welsh surf. "Riiiiight," he says, his eyes widening in alarm. "Ah. Oh dear." I linger on a soulful-looking headshot. His voice soars several octaves. "How very, er … startling." It's called fame, I say. Get used to it.• Skyfall opens in the UK today and the US on 9 November. Broken will be released in Spring 2013